The subject matter disclosed herein relates to improvements in flow monitoring technology for use in industrial processes, with particular discussion about embodiments of a liquid-level transmitter device that integrates with control systems for the industrial processes, the embodiments being configured to compensate for changes in operative characteristics of the device to generate measured values for liquid levels in a reservoir.
Level transmitters and like devices are useful to monitor liquid levels in a process line. These devices have particular utility to industrial processes typical of chemical, petro-chemical, oil & gas extraction and transportation, and the like. In one form, the devices can have a structure to convert buoyant action of one or more components into a measured value that reflects the level of liquid in a vessel or a reservoir. The structure can also communicate this measurement to a process control system that regulates operation of devices on the process line.
The structure can incorporate various components that operate to convey the buoyant action as torque (or torsion or rotation). These components can include shafts (and like tubular, elongate elements) that couple the buoyant component with a sensor and/or other element that generates the measurement. In one example, the shaft can rotate in response to the torque. The sensor can register the rotation of the shaft, effectively generating a value for the measured value that is proportional to the displacement of the buoyant component.
Unfortunately, accuracy of this value depends in large part on the operative characteristics of the structure. Because the structure is largely mechanical, small changes in physical properties, dimensions, and tolerances can frustrate the proportionality that the structure relies upon to generate accurate information about the level of liquid. Many of these changes relate to one or more operating temperatures (e.g., ambient or environment temperature, process temperature, device temperature, etc.). Nevertheless, these problems can permeate throughout the structure and, ultimately, induce errors in the value of the measurement.
Conventional devices employ several solutions to address issues of accuracy that arise in connection with the operative characteristics of level transmitter devices. In many cases, the solution relies upon manual entry of data to “artificially” rectify the error in the value of the measurement. This data may define temperature (e.g., process temperature) and/or other operating parameters (e.g., specific gravity, calibration parameters, etc.). The data may also include values for coefficients that algorithms use to compensate for changes that occur in the operative characteristics of the device. In other conventional devices, the data may include measurements, namely, temperature measurements from sensors disposed external, or outside of, the level transmitter device.
However, none of these solutions address accuracy issues across a broad swath of applications. Implementations that position the level transmitter device in hazardous areas, for example, can introduce conditions that distort measurements from external sensors and/or foreclose individuals from access to the level transmitter device. Moreover, data entry by individuals may exacerbate problems, particularly if the individual introduces inaccurate information that is meant to correct the error in the value of the measurement.